We propose to study the circular dichroism of double-stranded RNAs. First, we will measure the CD spectra of a set of synthetic RNA sequences. From these we will be able to determine whether the CD spectrum of an RNA is a nearest-neighbor property. The CD spectra of the synthetic RNA sequences will then be used as a basis for analyzing the spectra of natural double-stranded RNAs. The RNAs studied will be from virus particles of the fungus Penicillium chrysogenum. We also propose to study the condensate(s) formed by the ethanol-and-salt precipitation of doubde-stranded RNA. We will use CD and electron microscopic techniques. Past studies have shown that DNA condenses differently when in the A conformation, which is an RNA-like conformation, than when in the usual B conformation. We wish to determine whether RNA is restricted in the types of tertiary condensates it can form as a result of its inability to exist in a B conformation.